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Method for improved measurement of local physical parameters in a fluid-filled cavity

Inactive Publication Date: 2005-11-08
BRACCO RES USA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0012]The stabilized or encapsulated gas bubbles useful in the invention may be divided into several categories:stabilized gasmicrobubbles, gas-filled microcapsules/microballoons, and gas containing microparticles according to the definitions given in for example, in EP 554213 and U.S. Pat. No. 5,413,774.
[0013]The term “microbubble” specifically designates gas bubbles, in suspension in a liquid preferably also containing surfactants or tensides to control the surface properties and the stability of the bubbles. The term “microcapsule” or “microballoon” designates preferably air or gas-filled bodies with a material boundary or envelope, i.e. a polymer membrane wall. The term microparticle refers to gas-containing solid systems, for example microparticles (especially aggregates of microparticles) having gas contained therein or otherwise associated therewith (for example being adsorbed on the surface thereof and/or contained within voids, cavities or pores therein).
[0014

Problems solved by technology

The first method is accompanied by the disadvantages of an invasive procedure, i.e. creating pain and risk of infection.
The second, noninvasive method does not provide reliable or reproducible blood pressure values (Strauss A L, Roth F J, Rieger H.
WO 99 / 47045) have been hampered by inaccuracy and insensitivity
The Bouakaz article stated that this method is inaccurate for detecting small pressure changes on the order of 5-10 mmHg, which are clinically relevant (Bouakaz et al.
Therefore, this method is also lacking sensitivity when detecting small pressure changes.
Secondly, this method strongly depends on the size of the bubbles at the location where the pressure is to be measured.
With this new method small pressure changes (5-10 mmHg) can be measured, which is the main limitation of the methods described by aforementioned references.

Method used

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  • Method for improved measurement of local physical parameters in a fluid-filled cavity
  • Method for improved measurement of local physical parameters in a fluid-filled cavity
  • Method for improved measurement of local physical parameters in a fluid-filled cavity

Examples

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example 1

[0093]FIG. 4 shows the sub- and ultraharmonic energy curves (top and bottom, respectively) as a function of time for an air bubble with a radius of 2.2 μm as obtained by computer simulation. The curves were calculated, as described in the specification, for different values of the surrounding liquid pressure. The liquid pressure is indicated by the overpressure, i.e. the pressure value over the atmospheric pressure of 760 mmHg. The values for the overpressure were 0, 50, 100 and 200 mmHg. The different lines show the respective energy curves. From these curves the mean response time was calculated according to equation (2) and the values for the mean sub- and ultraharmonic response time are given in table 1 in the third and fourth column, respectively. As a reference, the time for the air bubble to completely disappear as a function of the overpressure is calculated by equation (1), and is given in the second column. By looking at the difference in sub- and ultraharmonic response ti...

example 2

[0095]This example shows the sensitivity of the new method to measure clinical relevant pressure differences of 10 mmHg, for an air bubble with a radius of 2.2 μm as obtained by computer simulation. The results of this example are shown in table 2. The overpressures range from 80 to 120 mmHg in steps of 10 mmHg. The difference in disappearance time (column 2 in table 2) ranges from 1.2 to 1.4 ms per 10 mmHg of pressure change. The difference in mean response time for the subharmonic (column 3 in table 2) ranges from 1.7 to 2.7 ms. The difference in mean response time for the ultraharmonic (column 4 in table 2) ranges from 2.1 to 2.8 ms. This means that by using the new method, the sensitivity increased by 40-100%, compared to methods that consider the complete disappearance of gas bubbles.

[0096]

TABLE 2Disappearance time, td, mean response times forsubharmonic, t_sub, and ultraharmonic, t_ul, as a functionof the overpressure.Pov [mmHg]td [ms]t_sub [ms]t_ul [ms]80108.440.241.390107.03...

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Abstract

The present invention relates to remotely determining local physical parameters in a fluid-filled cavity (e.g. heart cavities, blood vessels, industrial container) by means of ultrasound waves and encapsulated or stabilised gas bubbles. A measuring method, a method of diagnostic ultrasound of the same and an apparatus for remotely determining ambient physical local parameters of a fluid-filled cavity are disclosed.

Description

[0001]This application claims the benefit of provisional application 60 / 281,794 filed on Apr. 6, 2001.TECHNICAL FIELD[0002]The present invention relates to a noninvasive measuring method for remotely determining local physical parameters of a fluid-filled cavity, by means of ultrasound waves and encapsulated or stabilized gas bubbles (e.g. suspensions of stabilized microbubbles, microballoons or microparticles comprising gas).BACKGROUND OF THE INVENTION[0003]Physiological parameters of the cardiovascular system, such as blood pressure, temperature and gas concentration are important since they provide essential information concerning the state of health of organs and the patient. Currently, dynamic blood pressure measurements are mainly performed by catheterization, consisting of a pressure-sensing catheter that is inserted into the heart chamber or blood vessel, or by Doppler echocardiography using the simplified Bernoulli equation (Burton C. Physiology and biophysics of the circul...

Claims

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Application Information

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IPC IPC(8): A61B8/00G01L11/06G01N29/02G01N29/036G01L11/00G01N15/02G01N7/14G01N7/00G01N15/00A61B5/022A61B8/04A61K49/00
CPCA61B8/481G01L11/06G01N15/02G01N29/036G01N2015/0011G01N2291/02433G01N2291/02854G01N2291/02872
Inventor FRINKING, PETER J. A.ARDITI, MARCEL
Owner BRACCO RES USA